The most recent execution was part of an ongoing war between the Viagras cartel and Jalisco New Generation Cartel.

Grisly scenes as three bodies found hanging from bridge in suspected Mexico cartel attackReuters

For Mexican drug cartels, murder is a popular form of communication and recently a gang sent a clear message to its rival by posting a brutal beheading video on social media. The Viagras cartel in Michoacán state captured a rival hitman and decapitated him after making him confess his "sins".

The victim was a brother of a Jalisco New Generation Cartel (CJNG) member Juan Carlos Márquez Pérez, known as El Duende (The Goblin), who was arrested in 2015.

In the video, Duende's brother is seen talking directly to the camera before a hitman holds his head and beheads him with a carving knife. The gruesome style of filming assassinations is becoming a "signature move" in the Mexican underworld and is inspired by the Islamic State's own theatrical beheadings.

"This execution video is definitely out of character for the Viagras and appears to be an escalation in their use of violence against the CJNG cartel," security expert Robert Bunker told The Daily Beast. "A safe guess would be that their fight with CJNG may not be going well and they see the need to 'ramp up the terror' against that group in order to better protect their territories and illicit interests."

"The beheading technique is quite similar to Isis and has a long tradition in military combat as a strategy to terrorise the enemy," organised crime expert Gustavo Fondevila said of the recent footage. Just days before the assassination video was posted online, two severed human heads were found in a cooler outside the office of Mexican broadcaster Televisa in the city of Guadalajara.

The murders were committed by CJNG and the cooler in which the heads were placed also contained a threat to Jesús Humberto Boruel Neri, a high-ranking police official.

According to local reports, a second cooler was found near the federal court but the authorities choose not to disclose its contents.

A demonstrator on a silhouette that represents a victim of violence is painted by an activist of the organization Nos hacen falta (We are missing them), during a demonstration demanding justice for the victims of violence and drugs, at the Monument to the Revolution in Mexico City, Mexico, on 11 December, 2016REUTERS/Henry Romero